The Analytical Core is a central resource composed of two laboratories that facilitate-development and application of modern analytical methods to solve key problems encountered by the components of the Superfund Program. The first is the Superfund Analytical Laboratory which provides a range of instrument services with emphasis on mass spectrometry and chromatography and small molecule analysis. The second is the Accelerator Mass Spectrometry Facility with 2 AMS instruments at Lawrence Livermore National Laboratory for ultra trace analysis. Proteomic analysis is largely provided in Core B (formerly Core C) although the instrumentation in Core A is available for proteomic work. The Analytical Core provides walk-up instrumentation as well as services and research collaborations to the projects. The services include assistance with other campus facilities such as nuclear magnetic resonance (NMR). Core A advances many analytical technologies, including preparation, throughput and accuracy by developing robotic procedures, sample clean up, approaches to sample preparation and derivatization. Core A supports the development of both global and pathway selective metabolomic techniques and their applications to hypothesis generation and testing as well as for biomarker development. It carries out bioassay driven fractionation of hazardous mixtures, in collaboration with the projects and provides education for Superfund scientists in analytical chemistry. The LLNL component provides access to a variety of advanced instruments but focuses on the sub attomole (i.e. 10[-18]) sensitivity of AMS in support of projects using [14]C as a heavy isotopes. This technique for the first time allows human monitoring of metabolism of hazardous chemicals at environmentally realistic levels using exceptionally low levels of tracers. Priority targets for AMS are to quantify human metabolism of the insecticide permethrin and the personal care product triclocarban. Core A scientists provide one-on-one assistance in analytical chemistry, data generation and analysis and on going formal training in analytical techniques for Superfund researchers. Thus, Core A provides the broad analytical support necessary for developing and using biomarkers of exposure and effect.